1. Field of the Invention
The present invention relates to an electric toothbrush with a multi-position switch allowing for an automatic mode of operation.
2. Background Art
Use of electric, motorized toothbrushes used as an aid in cleansing teeth is well known. Typically these toothbrushes employ rotating, reciprocating, or oscillating motion, or a combination thereof, to effectuate the cleaning process.
A feature commonly found on these toothbrushes is a sliding on/off switch located on or near the handle portion of the toothbrush. The primary feature of such a switch is that it remains either in the xe2x80x9conxe2x80x9d position or the xe2x80x9coffxe2x80x9d position until the user manually changes it. With such a switch, the user has a limited number of choices. The toothbrush motor can be engaged prior to the brush head being placed in the mouth, or the user can wait until the brush head is placed within the mouth before engaging the motor. Both of these choices have inherent undesirable consequences.
When the user engages the motor prior to placing the brush head in the mouth, the rapid movement of brush head may cause the toothpaste to be shaken off the bristles. Conversely, if the user waits until the brush head is inside the mouth, and in particular in contact with the teeth, it may be difficult to engage the switch, depending on its position relative to the user""s hand.
Accordingly, it is desirable to provide an improved electric, motorized toothbrush that overcomes the above referenced shortcomings of prior art toothbrushes, by providing an automatic mode of operation.
The present invention provides an electric, motorized toothbrush that can be used in an xe2x80x9cautomaticxe2x80x9d mode. The automatic mode allows the user to insert the brush head into the user""s mouth before the motor is engaged and the brush head starts moving. Engagement of the motor is accomplished by one of a number of methods, each of which utilizes an operator sensitive switch located within the toothbrush housing. One method merely requires the user to bring the brush head into contact with one or more teeth; here, the downward force on the brush head actuates the switch. Another method relies on the force generated by the user""s grip to actuate the switch and start the motor. Yet another method involves the use of sensors in the handle such that the presence of the user""s hand actuates the switch that engages the motor. The rotation of the motor, through various mechanical linkages, causes the brush head to oscillate, facilitating tooth cleaning.
In a preferred embodiment, the toothbrush has a two-piece housing in which most of the components are located. The housing contains a handle portion and a head portion, connected by a neck portion. The handle portion contains a compartment for a plurality of batteries, held in place and electrically connected by an end cap. Also within the handle portion is a first switch, having an xe2x80x9coffxe2x80x9d position and an xe2x80x9cautomaticxe2x80x9d position.
A plurality of gears are operatively connected between the motor and a connecting arm. A spur gear, connected to the motor shaft, drives a ring gear which has an integral crank pin. A connecting arm is operatively connected between the crank pin and a shaft, the shaft being located substantially within the neck portion. In operation, this mechanism resembles a typical slider crank.
One end of the shaft is located in the head portion of the housing, and is operatively connected to a pinion which is attached to a brush head shaft located on the base side of the brush head. The pinion interfaces with a rack located within the head portion of the housing, thereby facilitating movement of the brush head.
In the preferred embodiment, a second switch is located substantially within the neck portion of the housing. This switch is characterized by two contact plates. The contact plates are not normally electrically connected; this keeps the electric circuit open. When a force is exerted on the brush headxe2x80x94e.g., when the brush head is in contact with the user""s teethxe2x80x94the two contact plates electrically connect, the circuit is closed, and the motor is engaged.
In an alternative embodiment, the second switch is located in the handle portion of the toothbrush. Here, the user squeezes a compressible portion of the handle, thereby closing the second switch. Different types of switches can be employed for this purpose, but the end result is the same. The motor will not rotate and the brush head will not move until the user squeezes the handle and actuates the second switch.
Another embodiment of the present invention also places the second switch in the handle portion; however, in this embodiment, sensors on the outside of the handle detect the presence of the user""s hand. Hence, the user need not apply a gripping force to the handle to actuate this switch, rather, mere contact with the sensors closes the switch and completes the circuit.
In each of these embodiments, the first switch can be a three-position switch instead of the two-position switch described above. The use of a three-position switch adds as an option, a continuous xe2x80x9conxe2x80x9d mode of operation. That is, the toothbrush could still be used in an xe2x80x9cautomaticxe2x80x9d mode, or turned off completely, but the addition of the continuous xe2x80x9conxe2x80x9d mode of operation would allow the toothbrush to be used in the manner of conventional motorized toothbrushes.